Polishing pad

ABSTRACT

Object: Providing a polishing pad that is deformable with a smaller force. Solution: A polishing pad ( 1 ) according to an aspect of the invention includes a substrate ( 2 ) made of a piece of non-woven fabric. The substrate ( 2 ) has a flat-plate shape extending in a first direction perpendicular to a thickness direction and in a second direction perpendicular to both the thickness direction and the first direction. The substrate ( 2 ) is divided into a plurality of blocks ( 3 ) arranged in the second direction and each extending in the first direction. A boundary portion ( 4 ) extending in the first direction is formed between each pair of the blocks ( 3 ), and a plurality of slits ( 6 ) are formed in the boundary portion ( 4 ). Each of the slits ( 6 ) is formed through the substrate ( 2 ) in the thickness direction and extends in first direction. The plurality of slits ( 6 ) that exist in the boundary portion ( 4 ) are spaced apart from each other in the first direction. A pair of the blocks ( 3 ) that are next to each other in the second direction are connected to each other by a connection portion ( 7 ) formed between the slits ( 6 ).

TECHNICAL FIELD

The invention relates to a polishing pad.

BACKGROUND ART

There is a known polishing pad that includes a substrate made from anon-woven fabric. For instance, the polishing pad disclosed in PatentDocument 1 is used for scouring a target object to remove dirt on thetarget object.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2011-189189

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

In some cases where a worker uses a polishing pad for cleaning, thepolishing pad has to be deformed (bent) to be fit to the shape of thetarget object. The worker scours the target object while keeping thepolishing pad deformed (bent). A worker using a polishing pad of theabove-described type has to apply a force to deform (bend) the polishingpad and to keep the polishing pad deformed (bent). Hence, there has beena demand for a polishing pad that is deformable (bendable) by a smallerforce to make the scouring work easier.

Means for Solving the Problem

A polishing pad according to an aspect of the invention includes asubstrate made of a piece of non-woven fabric. The substrate has aflat-plate shape extending in a first direction perpendicular to athickness direction and in a second direction perpendicular to both thethickness direction and the first direction. The substrate is dividedinto a plurality of blocks arranged in the second direction and eachextending in the first direction. A boundary portion extending in thefirst direction is formed between each pair of the blocks, and aplurality of slits are formed in the boundary portion. Each of the slitsis formed through the substrate in the thickness direction and extendsin first direction. The plurality of slits that exist in the boundaryportion are spaced apart from each other in the first direction. A pairof the blocks that are next to each other in the second direction areconnected to each other by a connection portion formed between theslits.

Effect of the Invention

The invention provides a polishing pad that is deformable (bendable)with a smaller force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a polishing pad according toan embodiment.

FIG. 2A is a drawing illustrating the polishing pad viewed from anX-axis direction. FIG. 2B is a drawing illustrating the polishing pad ina deformed (bent) state viewed from the X-axis direction.

FIG. 3 is a drawing illustrating a state of slits of the deformed (bent)polishing pad viewed from a thickness direction.

FIG. 4 is a drawing illustrating a model used for determining aY-axis-direction dimension of each block.

FIG. 5A is a drawing illustrating a polishing pad according to acomparative example viewed from the thickness direction. FIG. 5B is adrawing illustrating the polishing pad according to the comparativeexample viewed from the X-axis direction. FIG. 5C is a drawingillustrating the polishing pad in a deformed (bent) state according tothe comparative example viewed from the X-axis direction.

FIG. 6A and FIG. 6B are drawings illustrating polishing pads accordingto modified examples viewed from the thickness direction.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the invention will be described below with reference tothe attached drawings. Note that, in the following descriptions, thesame reference symbols have been assigned to elements that are the sameor equivalent, and that redundant descriptions thereof have beenomitted.

A polishing pad 1 according to an embodiment of the invention will bedescribed below with reference to FIG. 1. FIG. 1 is a perspective viewillustrating a polishing pad. As illustrated in FIG. 1, the polishingpad 1 includes a substrate 2. In this embodiment, a directionperpendicular to a thickness direction of the substrate 2 is defined asan X-axis direction (first direction) whereas a direction perpendicularto both the thickness direction and the X-axis direction is defined asan Y-axis direction (second direction). The substrate 2 has a flat-plateshape extending in both the X-axis direction and in the Y-axisdirection. The substrate 2 has principal surfaces 2 c and 2 d, which areopposite to each other in the thickness direction. In FIG. 1, thesubstrate 2 has its longer side extending in the X-axis direction andits shorter side extending in the Y-axis direction. The shape of thesubstrate 2 is not particularly limited. In the substrate 2, theproportion of the side in the X-axis direction to the side in the Y-axisdirection may be appropriately changed if necessary. The size of thepolishing pad 1 may be one that allows the worker to hold the polishingpad 1 while the worker is working with the polishing pad 1. Forinstance, the polishing pad 1 may have a thickness ranging from 20 to 40mm and a dimension ranging from 100 to 150 mm both in the X-axisdirection and in the Y-axis direction.

Firstly, some illustrative examples of the substrate 2 are describedbelow. The substrate 2 of this type is one using a water-soluble binder.The substrate 2 is made of a piece of non-woven fabric. The non-wovenfabric has an abrasive coat configured to hold abrasive particles. Somenon-woven webs suitable for use in abrasive cleaning articles are notlimited to particular ones, and are made of an air-laid, a carded, astitch-bonded, a spun-bonded, a wet-laid, or a melt-blown structure.Some examples of the fibers suitable for use in abrasive cleaningarticles are natural fibers, synthetic fibers, and mixtures thereof.Some preferred fibers are synthetic fibers made from polyester (e.g.,polyethylene terephthalate), nylon (e.g., hexamethylene adipamide andpolycaprolactam), polypropylene, acryl (formed from acrylonitrilepolymer), rayon, cellulose acetate, polyvinylidene chloride-vinylchloride copolymer, vinyl chloride-acrylonitrile copolymer, or the like.Some examples of the suitable natural fibers are cotton, wool, jute, andlinen fibers. The fibers to be used may be new, unused fibers.Alternatively, waste fibers may be used as well, for instance, thoserecycled fibers obtained by cutting garments and those obtained fromcarpet manufacturing processes, fiber manufacturing processes, ortextile fiber manufacturing processes. The fiber material may be uniformfibers, or may be composite fibers such as conjugated fibers (e.g.,co-spun sheath-core fiber). Providing an article whose web containsdifferent fibers in different portions (e.g., a first web portion, asecond web portion, and an intermediate web portion) is also within thescope of the invention. The web fiber may preferably be stretched andcrimped. Alternatively, the web fiber may be continuous filaments formedby an extrusion molding process and may be continuous fibers.

The abrasive coat is designed to make the substrate 2 hold the abrasiveparticles and to fix the abrasive particles to the substrate 2. Theabrasive coat contains a water-soluble binder. When the polishing pad 1is used, the water-soluble binder is exposed to a solvent. Until thattime, the water-soluble binder is solidified so that the abrasiveparticles can be held by and fixed to the non-woven fabric of thesubstrate 2. The solvent is one that is used for cleaning. Once thesolvent starts to solve the water-soluble binder, the abrasive particlesare released from the polishing pad 1. The water-soluble binder may bean oligomer or a polymer, or may contain copolymers and a blend thereof.Unlimited examples of polymers and copolymers that are suitable for useas the water-soluble binder are: polyethylene glycol, polyvinylpyrrolidone, polyvinyl pyrrolidone/vinyl acetate copolymer, polyvinylalcohol, carboxymethyl cellulose, hydroxypropyl cellulose starch,polyethylene oxide, polyacrylamide, polyacrylic acid, cellulose etherpolymer, polyethyloxazoline, polyethylene oxide ester, copolymer ofpolyethylene oxide ester and polypropylene oxide, polyethylene oxideurethane, and copolymer of polyethylene oxide urethane and polypropyleneoxide.

The water-soluble binder may be a surfactant. In addition, thewater-soluble binder may include a combination of various water-solublebinders containing a surfactant as a component. In addition, thewater-soluble binder may include a combination of various surfactants.

Some of the surfactants useful in the invention are those that areeasily soluble in water. In addition, the surfactant provides excellentfoamability, cleaning ability, oil-fat removing property in ordinarycleaning use in households. The surfactant helps remove coloring stains,grease, oil, soil, dirt, and deposits.

Some examples of the surfactants used for the abrasive cleaning articleof the invention are one or more kinds of anionic surfactants, cationicsurfactants, nonionic surfactants, and amphoteric surfactants, as wellas combinations of such surfactants. Desirable surfactants are thosegentle on the skin of the user and nontoxic. In a blend of one or morekinds of anionic surfactants, cationic surfactants, nonionicsurfactants, and/or amphoteric surfactants, the use of an anionicsurfactant in a higher concentration is desirable for enhancedfoamability and cleaning ability. This, however, is within the scope ofthe invention.

The abrasive particles are releasably fixed to the non-woven fabric ofthe substrate 2 by the water-soluble binder. Examples of the abrasiveparticles used in the manufacturing of the article according to theinvention include all the known abrasive materials, combinations andaggregates of such abrasive materials. Some examples of softer abrasivematerials are: inorganic materials such as flint, silica, pumice, andcalcium carbonate; organic polymer materials such as polyester,polyvinyl chloride, methacrylate, methyl methacrylate, polycarbonate,and polystyrene; and combinations of some of the above-mentionedmaterials. These, however, are not the only examples. Some examples ofharder abrasive materials are: aluminum oxides such as aluminum oxide,heat-treated aluminum oxide, and white aluminum oxide; silicon carbide;alumina zirconia; diamond; ceria, cubic boron nitride; garnet; andcombinations of some of the above-mentioned materials. These, however,are not the only examples.

In addition to the water-soluble binder and the abrasive particles, theabrasive coat may contain colorants, perfumes, fragrant oils,preservatives, humectants, anti-foaming agents, coupling agents,suspending agents, pigments, and antibacterial additives. Suchadditional components are well known to the persons in the relevanttechnical field.

Secondly, different illustrative examples of the substrate 2 aredescribed below. The substrate 2 of this type is one using athermosetting adhesive as the binder. Some preferred non-woven fabricsare those made from thermoplastic organic fibers such as polyamide(e.g., nylon 6 and nylon 6,6 made from polycaprolactam and/orpolyhexamethyl adipamide), polyolefin (e.g., polypropylene andpolyethylene), polyester (e.g., polyethylene terephthalate), andpolycarbonate. Commonly used non-woven fabrics are those made from nylonand polyester fibers.

In general, the fiber has a thickness (diameter) ranging from 19 to 250μm, approximately. In general, the non-woven fabric has a thicknessranging from 2 to 50 mm, approximately. Once arranged in place, thefibers are bonded to one another at intersections and/or contact pointsby frictional forces, adhesive forces, etc. The bonding of fibers may beachieved by melting the fibers or by the use of a special adhesiveagent.

Adhesive agents are used for boding the fibers of the non-woven fabricto one another or for bonding the fibers of the non-woven fabric to theabrasive particles. A single adhesive agent may be used both for bondingthe fibers of the non-woven fabric to one another and for bonding thefibers of the non-woven fabric to the abrasive particles. Alternatively,different adhesive agents may be used for the above-mentioned differentpurposes. When a single adhesive agent is used, the bonding of thefibers of the non-woven fabric to each other and the bonding of thefibers of the non-woven fabric to the abrasive particles may be carriedout simultaneously in the manufacturing process.

A first adhesive agent to be used for bonding the fibers of thenon-woven fabric to one another may be such thermosetting adhesiveagents as aqueous suspensions and organic solvent solutions of epoxy,melamine, phenol, isocyanate and isocyanurate resins, or suchrubber-based polymer solutions or suspensions as SBR, SBS, and SIS.

The non-woven fabric is formed by hardening the adhesive agents appliedby a method such as a dip coating, a roll coating, and a spray coating.

The method of manufacturing the substrate 2 is not particularly limited.For instance, the substrate 2 may be formed by, firstly, stacking aplurality of fiber sheets one upon another to form a layered body andthen sticking the sheets in the layered body together with an adhesiveagent. Alternatively, the substrate 2 may be formed by collectingextruded fibers together, then sticking the fibers together, and thencutting the solid layered body with a die.

The substrate 2 is divided into a plurality of blocks 3 arranged in theY-axis direction and each extending in the X-axis direction. The blocks3 refer to some areas of the substrate 2 located between a first endportion 2 a and a second end portion 2 b in the X-axis direction. Theblocks 3 are the areas with no slits 6 extending in the X-axis direction(details of the slits 6 will be described later). In the substrate 2,each of the blocks 3 extends in a band shape between the end portion 2 aand the end portion 2 b. While the substrate 2 is in a deformed state,the blocks 3 become the main areas that are brought into contact withthe target object to polish the surface of the target object. Each ofthe blocks 3 is defined to have a predetermined width in the Y-axisdirection. How to set the pitch at which the blocks 3 are arranged willbe described later.

Between a pair of the blocks 3, a boundary portion 4 extending in theX-axis direction is formed. Each of the boundary portion 4 has aplurality of slits 6 each of which is formed through the substrate 2 inthe thickness direction and each of which extends in the X-axisdirection. Each of the slits 6 extends in the thickness direction fromthe principal surface 2 c to the principal surface 2 d. The slits 6 areformed by: providing a tool having a plurality of plate-shaped blademembers standing on a base member; and then pressing the substrate 2against the tool to allow the blade members to penetrate the substrate2. In each of the boundary portions 4, the plurality of slits 6 arespaced apart from one another in the X-axis direction. The portionbetween one slit 6 and another slit 6 serves as a connection portion 7configured to connect one block 3 to another block 3. To put itdifferently, a pair of the blocks 3 that are next to each other in theY-axis direction are connected to each other by the connection portion 7formed between the slits 6.

In FIG. 1, some of the boundary portions 4 are indicated by imaginarylines. Each of the boundary portions 4 is a straight line extendingstraight in the X-axis direction. A plurality of the slits 6 and aplurality of the connection portions 7 are alternately arranged in eachof the boundary portion 4. To put it differently, each of the “boundaryportions” corresponds to an imaginary line drawn to overlap the slits 6when viewed in the thickness direction and extending to the end portions2 a and 2 b. Hence, each of the boundary portions 4 refers to animaginary line configured to virtually separate a block 3 from anotherblock 3. Each of the “slits” refers to a cut formed in the substrate 2.While the substrate 2 is in a normal state (the state illustrated inFIG. 1), edge portions 6 a and 6 b of each slit (see FIG. 2 and FIG. 3)are in contact with or adjacent to each other in the principal surface 2c. If a force is applied to widen each of the blocks 3 in the Y-axisdirection, the distance between the edge portions 6 a and 6 b of eachslit 6 increases to separate the edge portions 6 a and 6 b separatedfrom each other in the principal surface 2 c. Each of the “connectionportion” refers to a portion of the imaginary line of the boundaryportion 4. The portion has no slit 6. Even if a force is applied towiden each of the blocks 3 in the Y-axis direction, the connectionportion 7 fixes the blocks 3 that are next to each other by preventingthe blocks 3 from departing from each other and thus by leaving no suchopening as the slit 6.

As such, by forming slits in some portions of the substrate 2, thedeformation (bending) of the substrate 2 in the Y-axis direction by aworker leaves the substrate 2 in a state where openings appear at thepositions of the slits 6 as illustrated in FIG. 2 and FIG. 3. At eachslit 6, an opening is formed in the substrate 2 so that the edgeportions 6 a and 6 b located on the outer peripheral side for thedeformation (bending) can go away from each other. In contrast, if thesubstrate 2 is deformed (bent) in the X-axis direction, the substrate 2is deformed (bent) without leaving any opening at the positions of theslits 6. Hence, the worker can deform (bend) the substrate 2 more easilyin the Y-axis direction than in the X-axis direction. For instance, thesubstrate 2 may have a bending strength in the Y-axis direction that isfrom 10 to 80%, preferably from 15 to 50%, of the bending strength ofthe substrate 2 in the X-axis direction. The bending strength isobtained by measurement using a Gurley-type bending stiffness tester andfollowing a measurement method that conforms to the bending repulsionmethod A of JIS L-1096 and JAPAN TAPPI NO. 40. Note that when thepolishing pad 1 is deformed (bent), a spring-back force (repulsiveforce) is generated in the polishing pad 1 itself. The repulsive forcereturns the polishing pad 1 to a substantially flat state when the forcebending the polishing pad 1 is released. In addition, the repulsiveforce has an effect to allow the polishing pad 1 to fit closely to(stick to) the palm of the worker while the worker is working with thepolishing pad 1.

In this embodiment, the connection portions 7 formed in the boundaryportion 4 located on a first side, in the Y-axis direction, of a block 3are located at different positions in the X-axis direction from thepositions of the connection portions 7 formed in the boundary portion 4located on a second side, in the Y-axis direction, of the same block 3.Note that the phrase “located at different positions” only means thatthe position of the center, in the Y-axis direction, of one connectionportion 7 is different from the corresponding position of the otherconnection portion 7. Hence, a portion, in the Y-axis direction, of oneconnection portion 7 may overlap a portion of the other connectionportion 7. The slits 6 formed in the boundary portion 4 located on afirst side, in the Y-axis direction, of a block 3 are located atdifferent positions in the X-axis direction from the positions of theslits 6 formed in the boundary portion 4 located on a second side, inthe Y-axis direction, of the same block 3. To put it differently, ofevery two adjacent boundary portions 4, one boundary portion 4 has slits6 that form a zigzag pattern together with the slits 6 of the otherboundary portion 4. A structure like the above-described one where aplurality of slits 6 are arranged in a zigzag pattern may be referred toas a skip slit structure. In this embodiment, the slits 6 in the twoboundary portions 4 located at every other line are located at theidentical positions to one another, and so are the boundary portions 4in such two boundary portions 4. Hence, a zigzag pattern of the slits 6is formed by sets of boundary portions 4, each set including a pair ofthe boundary portions 4.

Each block 3, each slit 6, and each connection portion 7 in theabove-described configuration may have dimensions that are notparticularly limited but set in the following way, for instance. Thedimension, in the Y-axis direction, of each block 3 may range from 2 to40 mm, preferably from 2 to 20 mm. The dimension, in the X-axisdirection, of the each slit 6 may range from 5 to 50 mm, preferably from10 to 30 mm. The dimension, in the X-axis direction, of each connectionportion 7 may range from 5 to 50 mm, preferably from 10 to 30 mm.

Now, descriptions will be provided below concerning an exemplar methodof setting the dimension, in the Y-axis direction, of each block 3. Forinstance, when a target object 30 having a circular cross section asillustrated in FIG. 4 is polished by the use of the polishing pad 1, thepolishing pad 1 is desirably in contact with the target object 30 atleast 8 positions located in the circumferential direction. The modelillustrated in FIG. 4 assumes that when the substrate 2 of the polishingpad 1 is deformed (bent) to cover the target object 30, each block 3becomes substantially straight and the substrate 2 is bent at thepositions of the boundary portions 4. In this case, the substrate 2 isbrought into contact with the target object 30 at predetermined pointsof the blocks 3. In FIG. 4, an octagon is drawn with dashed-dotted lineson the outer circumference of the target object 30 to indicate thepolishing surface of the substrate 2. Here, when the target object 30has a diameter of 50 mm, a dimension of 19.6 mm is obtained by dividingequally the outer circumference of the target object 30 into 8.

Hence, the dimension, in the Y-axis direction, of each block 3 maypreferably be not greater than 20 mm, approximately.

Next, description will be provided concerning advantageous effects ofthe polishing pad 1 according to this embodiment.

The polishing pad 1 is including the substrate 2 made of a piece ofnon-woven fabric. The substrate 2 has a flat-plate shape extending inthe X-axis direction perpendicular to the thickness direction and in theY-axis direction perpendicular to both the thickness direction and theX-axis direction. The substrate 2 is divided into a plurality of theblocks 3 arranged in the Y-axis direction and each extending in theX-axis direction. The boundary portion 4 extending in the X-axisdirection is formed between each pair of the blocks 3, and a pluralityof the slits 6 are formed in the boundary portion 4. Each of the slits 6is formed through the substrate 2 in the thickness direction and extendsin the X-axis direction. The plurality of slits 6 that exist in theboundary portion 4 are spaced apart from each other in the X-axisdirection. A pair of the blocks 3 that are next to each other in theY-axis direction are connected to each other by the connection portion 7formed between the slits 6.

For instance, a polishing pad 100 according to a comparative exampleillustrated in FIG. 5 has no such slits as those that are provided inthis embodiment. In the case of the comparative example, when the workertries to deform (bend) the polishing pad 100, a resistance force againstthe bending of the substrate 2 is generated. Hence, the worker needs toapply a greater force to deform (bend) the polishing pad 100. Incontrast, the polishing pad 1 according to this embodiment has slits 6formed in the boundary portions 4 between the blocks 3 of the substrate2 and each extending in the X-axis direction. When a force is applied tobend the substrate 2 in the Y-axis direction, the substrate 2 leavesopenings that easily widen at the positions of the slits 6. Hence, whenthe worker tries to deform (bend) the polishing pad 1, the substrate 2can be deformed (bent) easily by allowing the slits 6 to widen. Inaddition, even if such slits 6 are formed, the boundary portions 4include the connection portions 7 configured to connect the blocks 3 toeach other prevent the blocks 3 from being cut off from each other.Hence, only a reduced force is needed to deform (bend) the polishing pad1.

The connection portions 7 formed in the boundary portion 4 located on afirst side, in the Y-axis direction, of a block 3 may be located atdifferent positions in the X-axis direction from the positions of theconnection portions 7 formed in the boundary portion 4 located on asecond side, in the Y-axis direction, of the same block 3. For instance,if, as illustrated in FIG. 6A later, the connection portions 7 that arenext to each other in the Y-axis direction are formed at the identicalpositions to each other in the X-axis direction, a greater resistanceforce against the bending of the substrate 2 is generated at positionswhere the connection portions 7 are contiguously formed as describedabove. In contrast, if the connection portions 7 that are next to eachother in the Y-axis direction are located at different positions, in theX-axis direction, from each other, the connection portions 7 can bedispersed to prevent the resistance force against the bending frombecoming greater.

The substrate 2 may have a bending strength in the Y-axis direction thatis from 10 to 80% of the bending strength of the substrate 2 in theX-axis direction. In this case, the worker can bend easily the polishingpad 1 to work with the polishing pad 1.

The dimension, in the Y-axis direction, of the block 3 may range from 2to 40 mm, the dimension, in the X-axis direction, of the slit 6 mayrange from 5 to 50 mm, and the dimension, in the X-axis direction, ofthe connection portion 7 may range from 5 to 50 mm. In this case, theworker can bend easily the polishing pad 1. In addition, a sufficientstrength of the polishing pad is secured.

The polishing pad 1 is including the substrate 2 made of a piece ofnon-woven fabric. The substrate 2 has a flat-plate shape extending inthe X-axis direction perpendicular to the thickness direction and in theY-axis direction perpendicular to both the thickness direction and theX-axis direction. In the substrate 2, a slit 6 extending in thethickness direction from the first principal surface 2 c in thethickness direction and extending in the X-axis direction in theprincipal surface 2 c is formed and a plurality of slits 6 are formed inthe Y-axis direction.

In the polishing pad 1, the substrate 2 has the slit 6 extending in thethickness direction from the first principal surface 2 c in thethickness direction and extending in the X-axis direction in theprincipal surface 2 c. When a force is applied to bend the substrate 2in the Y-axis direction, the substrate 2 leaves an opening that easilywidens at the position of the slit 6. In addition, a plurality of slits6 are formed in the Y-axis direction. Hence, the slits 6 are opened at aplurality of positions in the Y-axis direction. The entire substrate 2can thus be deformed (bent) easily. Accordingly, only a reduced force isneeded to deform (bend) the polishing pad 1.

The present invention is not intended to be limited to the embodimentdescribed above, but allows appropriate modifications when necessary.

The arrangement of the slits 6 is not limited to those described in theabove-described embodiment. For instance, in the polishing pad 1illustrated in FIG. 6A, the connection portions 7 formed in the boundaryportion 4 located on a first side, in the Y-axis direction, of a block 3are identical positions, in the X-axis direction, to the correspondingconnection portions 7 formed in the boundary portion 4 located on asecond side, in the Y-axis direction, of the same block 3. As such, theslits 6 do not have to be arranged in a zigzag pattern. In addition, inthe embodiment illustrated in FIG. 1, every two boundary portions 4 forma set and sets of such boundary portions 4 form a zigzag pattern ofslits 6. In lieu of this way of forming a zigzag pattern, an alternativeway of forming a zigzag pattern may be employed where as illustrated inFIG. 6B, even more boundary portions 4 form a set, and the sets of suchboundary portions 4 form a zigzag pattern of slits 6. The arrangementpattern of the slits 6, however, may be irregular one.

In addition, the slits 6 in the above-described embodiment are formedthrough the substrate 2. In lieu of this configuration, the slits 6 maybe formed not through the substrate 2. For instance, each slit 6 mayextend in the thickness direction from the principal surface 2 c of thesubstrate 2 to stop at a predetermined position in the substrate 2without reaching the principal surface 2 d.

In the above-described embodiment, each of the slits is formed to extendonly in the X-axis direction. In addition to these, an extra slit orextra slits may be formed to extend in the Y-axis direction. In such acase, the polishing pad can be deformed (bent) easily in the X-axisdirection, as well.

In the above-described embodiment, a rectangular-plate-shaped member isemployed as an exemplar substrate of the polishing pad. The shape of thesubstrate, however, is not particularly limited. The slit structure maybe applied to any type of substrate. For instance, the slit structuremay be applied to a flap brush, a unitized wheel, a unitized pad, abevel, a wheel, and the like.

1. A polishing pad comprising a substrate made of a piece of non-wovenfabric, wherein the substrate has a flat-plate shape extending in afirst direction perpendicular to a thickness direction and in a seconddirection perpendicular to both the thickness direction and the seconddirection; the substrate is divided into a plurality of blocks arrangedin the second direction and each extending in the first direction; aboundary portion extending in the first direction is formed between apair of the blocks, a plurality of slits are formed in the boundaryportion through the substrate in the thickness direction and each of theslits extends in the first direction, the plurality of slits that existin the boundary portion are spaced apart from each other in the firstdirection; and a pair of the blocks that are next to each other in thesecond direction are connected to each other by a connection portionformed between the slits.
 2. The polishing pad according to claim 1,wherein the connection portion of the boundary portion formed on a firstside, in the second direction, of the block is located at a differentposition in the first direction from the position of the connectionportion of the boundary portion formed on a second side of the block. 3.The polishing pad according to claim 1, wherein the substrate has abending strength in the second direction that is from 10 to 80% of thebending strength in the first direction of the substrate.
 4. Thepolishing pad according to claim 1, wherein the block has a dimension inthe second direction ranging from 2 to 40 mm, the slit has a dimensionin the first direction ranging from 5 to 50 mm, and the connectionportion has a dimension in the first direction ranging from 5 to 50 mm.5. A polishing pad including a substrate made of a piece of non-wovenfabric, wherein the substrate has a flat-plate shape extending in afirst direction perpendicular to a thickness direction and in a seconddirection perpendicular to both the thickness direction and the firstdirection, in the substrate, a slit extending in the thickness directionfrom a first principal surface in the thickness direction and extendingin the first direction in the principal surface is formed, and aplurality of the slits are formed in the second direction.